Gravity powered casing pump



Dec. 17, 1963 o. v. REYNOLDS GRAVITY POWERED CASING PUMP 3 Sheets-Sheet1 Filed March 20, 196 1 arm 1/. Reynolds v INVENTOR.

Dec. 17, 1963 '0, v. YN L 3,114,327

" GRAVITY POWERED CASING PUMP 3 Sheets-Sheet 2 7 Filed March 20. 19610270 V. Reynolds INVENTOR. e052.

BY gin 7 0 6 ..I w 4 6 x w 4 2 6 4 I l l I I I I I J 2 2 J l 6 by 0 6 V6 5 6 4, n 4 3 w Dec. 17, 1963 o. v. REYNOLDS GRAVITY POWERED CASINGPUMP 3 Sheets-Sheet 3 Offo l4 Reyna/d5 1N VEN TOR.

Filed March 20, 1961 BY m United States Patent 3,114,327 GRAVITY POWEREDCASING PUMP Otto V. Reynolds, Bloomfield, N. Mex, assignor of one-halfto L. G. Johnson Filed Mar. 20, 1961, Ser. No. 96,828 17 Claims. (Cl.103-158) This invention comprises a novel and useful gravity poweredcasing pump and more particularly relates to a reciprocating pump forproducing liquids from deep wells.

In the recovery of fluids such as petroleum or water from well bores, itsometimes occurs that owing. to economical reasons a relatively smallbore of five inches or less has been drilled into the productiveformation and the fluid produced from pump tubing within the casing ofthis bore is frequently at a rate of flow which is less than theproductive capacity of the formation penetrated by the well bore. Whenthis condition occurs, the well operator fails to obtain the maximumoutput and therefore the maximum profit from the well owing to the lackof adequate flow capacity.

It is therefore the primary purpose of this invention to provide anapparatus to eflectively overcome the foregoing difficulty and enable amaximum production from the well which is limited only by the volumetriccapacity of the casing of the Well.

More specifically, it is an object of the present invention to provide abottom hole type of reciprocating pump in which the entire Well casingis employed as the pump tubing string so as to obtain the utmost volumeof delivery from the well.

It is a further important object of the invention to provide anapparatus in accordance with the foregoing object which is capable ofbeing operated by conventional wire line equipment and will notnecessitate the weight of the pumping string as well as the expensethereof which are incident to pumping by a rigid pumping string orsucker rod string.

Still another purpose of the invention is to provide a bottom holereciprocating pump which shall reduce to a minimum the powerrequirements for operating the pump and which shall be so constructedthat gravity alone may be relied upon as the actuating means to effectthe downward pumping stroke while the operation of the wire line isutilized simply to lift the reciprocating mass of the pump assembly inpreparation for the next pumping stroke.

In carrying out the principles of this invention there is utilized anovel packer assembly which is appropriately secured and positioned inthe lower end of the well casing to completely seal oif the bottom holefrom the casing thereabove so that the entire casing above the packingmember may be utilized as the pump tubing of the apparatus.

Yet another object of the invention is to provide a packer assembly inaccordance with the preceding object which shall be provided with ameans for supporting the packer assembly in position from the bottom ofthe well bore and wherein the packer assembly itself shall support andfixedly carry a stationary piston which cooperates with and is disposedin a reciprocating gravity lowered and wire line lifted pump cylinder.

A still further and very important object of the invention is to providean apparatus in which the entire arrangement of reciprocating pumpbarrel, stationary piston, packer assembly and a supporting tailpipetherefor may be connected together as a unitary subassembly whereby theymay be lowered into or removed from a well bore by conventional wireline and when positioned in a well bore may be operated as a bottom holepump by the wire line.

3,114,327 Patented Dec. 17, 1963 "ice A further and more specific objectof the invention is to provide in an assembly of the character above setforth a packer construction in which the packer may be expanded into itssealing engagement with the well casing through the weight of the pumpas the assembly is lowered into the bottom hole of a well; and wherebythe weight of the liquid column from the packer to the surface may beutilized to retain the packer in a fluid tight sealed engagement withthe well bore; and whereby the packer and the entire assembly may bereadily retrieved by a wire line.

And a final important object of the invention to be specificallyenumerated herein resides in the provision of a pumping apparatus inaccordance with the foregoing objects wherein an automatically operatedventing or dumping valve is incorporated into the packer constructionwhich valve will be closed when the device is in normal pumpingposition, and which valve will be opened during reset of the device intoa well bore by the wire line and during withdrawal of the device fromthe well bore by the wire line to thereby permit the flow of fluidthrough the packer assembly and facilitate such lowering or lifting ofthe device.

FIGURE 1 is a view in central elevation through a portion of a casedwell bore and showing the position of the parts of the pump subassemblyin accordance with this invention during vertical travel of the assemblyby a wire line in the well casing;

FIGURE 2 is a view similar to FIGURE 1 but showing the position of theparts when the pumping subassembly is installed in a cased well bore andis in readiness for pumping operations;

FIGURE 3 is a view similar to FIGURES l and 2 but shows the position ofthe parts during operation of the pump and when the latter is in theupper position of reciprocation of the pump barrel in readiness forbeginning of the gravity operated pumping stroke;

FIGURES 4 and 5 are enlarged detailed views in central vertical sectionof the upper and lower portions respectively of the reciprocating pumpand the packer component of the assembly in the position assumed bythese parts during their vertical travel into or out of the well bore;

FIGURES 6 and 7 are horizontal sectional detailed views takenrespectively substantially upon the plane indicated by the section lines66 and 7-7 of FIGURES 3 and 4; and

FIGURE 8 is an exploded group perspective view showing the variouscomponents of this pump subassembly in their disassembled relation.

In the accompanying drawings the numeral 10 designates a portion of awell casing for a well bore extending from the surface to any suitablesubterranean formation for producing liquids therefrom such as oil orwater. The pump assembly or subassembly of this invention is adapted foruse in a well casing of this character and is particularly advantageousin its effects when the well casing is one of a relatively small ornarrow diameter. The basic concept of this invention resides in theusing of the well casing itself as the pump tubing through which theliquid from the formation is produced, thus dispensing with the usualpump tubing which is ordinarily disposed in such a Well casing and whichpump tubing therefore restricts the maximum flow of liquid from theformation to a rate of flow which is considerably less than that whichcould be accommodated by the well casing. In some instances it will bepreferred to initially install the casing pump of this invention in thewell casing 10-' when the well is initially produced, while in otherinstances it will be advantageous to convert a well of this characterfrom the employment of a relatively small in diameter pump tubing to theuse of the well casing as the pump tubing. In this latter event, theconventional pump tubing and bottom hole pump are pulled from the Welland are then replaced by the pump subassembly of this invention which iscarried by and is manipulated by a conventional wire line rather than bya rigid sucker rod or pumping string, and is both inserted into the wellbore and withdrawn from the 'Well bore by the use of the wire line.

FIGURE 1 and FIGURES 4 and 5 illustrate the construction and arrangementof the components of the bottom hole pump subassembly in accordance withthis invention with these components to be illustrated in the positionwhich they assume when the device is being lowered into or withdrawnfrom a well casing.

Shown at 12 is the lower end of a wire line by which the device is to belifted, lowered and operated, it being understood that a conventionalrope socket, not shown, is utilized for securing the wire line to thepump assembly.

The pump assembly includes as its main components a reciprocating pumpbarrel 14 which may be of any size desired which can be loosely receivedin the well casing for reciprocation therein as Well as for trips intoand out of the well casing. Supported and carried by the pump barrel 14in a manner to be subsequently set forth is a packer assembly indicatedgenerally by the numeral 16, while a tailpipe 18 comprises a supportmeans or anchor for the packer assembly and performs certain otherfunctions as subsequently set forth. A centralizer 20 is disposedbetween the Wire line or rope socket which is designated generally bythe numeral 22 and the pump barrel 14.

Referring now especially to FIGURE 4 it will be observed that the pumpbarrel 14 has a relatively large cylindrical chamber or bore 24 openingupwardly through its lower end and which provides the cylindricalworking chamber 26 of the pump. The lower end of this barrel is closedas by a closure cap or end plug 28 having an aperture or bore 30therethrough which guidingly accommodates the hollow tubular piston rod32. Freely slidable within the chamber 26 is the pump piston 34 havingan axial passage 36 therethrough in which is secured in any suitablemanner the upper open end of the piston rod 32. A standing valveassembly 38 is provided for controlling the communication between theupper open end of the piston rod 32 and the chamber 26 above the piston34. By way of example, this standing valve assembly includes acounterbore 40 in the upper end of the piston 34 in which is received aplate or disk 42 comprising a valve seat and an upwardly openingball-type of check valve 44 cooperates therewith, being retained inassociation with the seat by a slotted valve cage 46 which isscrew-threadedly engaged in the counterbore.

The upper end of the pump barrel 14 is provided with a delivery passage50 extending axially therethrough whose upper end is provided with acounterbore 52. The traveling valve assembly indicated generally by thenumeral 54 is engaged in this counterbore, consisting of a fiat plate ordisk 56, apertured as at 58 and which is controlled by the upwardlyopening non-return ball valve 60. A cylindrical hollow tubular body orsleeve 62 has its lower end threadedly engaged in the counterbore 52 andconstitutes a cage or closure for the traveling valve. This sleeve isprovided with a series of apertures or ports 64 which establishcommunication between the pump chamber 26 through the traveling valveassembly and into the casing above the pump barrel.

As will be understood, the rope socket 22 is fixedly secured to or mayconstitute an integral part of the member 62.

A centralizer 66 in the form of a cylindrical body of rubber or othersimilar yieldable and wear-resisting material is bonded or otherwisefixedly secured to and surrounds the member 62 and is of sufficientdiameter to slidably engage the well casing to act as a guide for theupper end of the pump barrel during travel of the latter into and out ofthe well bore. As shown best in FIGURE 8, the centralizer body 66 isprovided with a plurality of axially extending longitudinal channels orgrooves 68 in its periphery which constitute and are of sufiicient sizeand total cross-sectional area to permit substantially unrestricted flowof the fluid discharged from the traveling valve upwardly past thecentralizer and up the casing to the surface.

By virtue of its rigid connection to the upper end of the reciprocatingpump barrel the centralizer acts as a guide to prevent rubbing of thepump barrel against the well casing during its passage therethrough.

Referring now specifically to FIGURE 5 it will be observed that thepacker assembly 16 has a conical upper section 70 which is of aresiliently deformable material such as rubber or the like and is bondedto or fixedly secured to and surrounds the hollow piston rod 32 beingretained between upper and lower retaining members such as the upperplate 72 having a hub 74 suitably rigidly attached to the piston rod 32,and a lower retainer 76 in the form of a collar which is fixedly securedto the piston rod and is received in a recess 78 in the lower end of theupper packer section 70. It is particularly to be noted that theexterior surface of the packer section '70 is conical in shape, and hasa downwardly convergent tapering conical exterior surface 80 thereon.

The lower packer section consists of a main body portion 82 likewise ofa resiliently deformable material such as rubber and whose externaldiameter is such as to be slidable in the well casing 10 in closeproximity to the latter during travel of the device into and out of awell casing. The lower section is provided with a conical recess orcavity 84 which is upwardly divergent and which is sufficientlycomplementary to the conical exterior surface 80 of the upper section towedgingly receive the latter therein. The bottom surface of the lowersection is recessed or counterbored as at 86 to receive therein and tobondingly engage upon a metallic body or plug 88. This plug has a boreor passage 90 therethrough for slidingly receiving the piston rod 32 sothat the lower section is thus slidingly mounted upon the piston rodwhile the upper section 70 is fixedly secured upon the latter.

A stop means is provided for limiting relative sliding movement of thepiston rod through the lower packer section, and for this purpose thereis provided a nut 92 threadingly engaged upon the lower threaded end ofthe piston rod and which nut is adapted to abut against the bottomsurface 24 of an internally threaded recess 96 in the bottom face of thebody 88. A tailpipe or anchor means for the packer assembly is providedconsisting of a tubular member 98 whose upper end is threadedly engagedin the counterbore 96, whose lower end is adapted to rest upon thebottom of the well bore as shown in FIGURES 2 and 3 for supporting thepacker assembly in a fixed position adjacent the bottom of the wellbore, while the tailpipe is further provided with a plurality ofapertures or ports therethrough as at 100 which establish continuouscommunication between the interior of the tailpipe and the interior ofthe piston rod 32 and the bottom of the well bore below the packerassembly.

The piston rod is further provided below the upper packer section 70with a series of ports 102 which in the separated position of the twopacker sections as shown in FIGURE 5 establish free communication withthe space above the lower packer section and the interior of thetailpipe 98 and thus through the ports 100 with the interior of the wellcasing below the packer assembly. These ports and their cooperation withthe packer assembly constitute an unloading valve which forms a furtherimportant component of this invention.

The operation of this bottom hole pump subassembly is as follows:

When the components of the device are assembled together in the positionshown in FIGURES 1, 4 and 5 in readiness for lowering in a well boreupon the lower end of a wire line, it will be observed that the pumpbarrel 14 depends from the member 62 which latter is carried by the wireline. A piston is at the bottom of the pump chamber 26 and is thuscarried by and rests upon the end plug 28. The pump rod in turn by meansof the stop member 92 supports the lower packer section 82 as shown inFIGURE 5 so that at this time the unloading ports 102 are exposed to thespace above the lower packer, with the tailpipe 98 dependingtherebeneath. In this position as the device is lowered into a well borethe fluid in the well can freely pass upwardly through the openings inthe tailpipe, through the open lower end of the piston rod, then upthrough the unloading ports 102 and about the upper packer section 80,then upwardly around the pump barrel and by means of the channel 68 canpass above the centralizer. Thus there is substantially no obstructionor resistance to downward travel of the subassembly into a well bore. Ina similar manner, when the pump assembly is being pulled from the wellbore, the parts will assume the same position so that the fluid columnabove the packer assembly will thus be vented through the unloadingvalve formed by the ports 162, the lower end of the piston rod 32 andthe openings 100 in the tailpipe 98. Thus there will be no resistance orswabbing action efiected during withdrawal of the device from the wellbore.

From the position of FIGURE 1, the device is lowered into the well 'ooreuntil the anchor or packer support means 98 has its lower end engagingthe bottom of the well bore as shown in FIGURES 2 and 3. It will beunderstood that for this purpose the tailpipe is of sufficient length toposition the packer above the productive formation from which fluids areto be pumped to the surface. As soon as the anchor means engages thebottom of the well bore, the lower packer section ceases its downwardmovement. Thereupon, continued lowering of the Wire line through theweight of the pump barrel 14 continues to lower the latter and with itthe piston 34 and the piston rod 32. As the piston rod lowers, the upperpacker section 78 engages in the recess 84 of the lower packer section82, so that a wedging engagement is now effected. At the same time theunloading ports 192 now lie below the cavity 84 and thus are no longereffective to permit the flow of fluid between the tailpipe and thecavity 84.

As the pump barrel continues to lower, from the 'views as shown inFIGURE 2 to that shown in FIGURE 3, the pump barrel gradually slidesdownwardly upon the now stationary piston until the latter reaches itsuppermost position in the pump barrel, as shown in FIGURE 3, at whichtime the weight of the pump barrel now forcibly pushes the upper packersection 79 into a tight wedging engagement with the lower packer section82 thus radially expanding the latter into a fluid tight seal with thewall of the casing. At this time, the weight of the parts and the weightof any fluid column subsequently supported by the packer will maintzu'na secure fluid tight seal of the packer with the wall of the casingduring the vertical reciprocation of the pump barrel in the pumpingaction. The pump is now ready for use, and the wire line is now raisedand lowered through a sufiicient movement to effect a reciprocation ofthe pump barrel so as to cause a relative travel of the pump piston,which remains stationary, throughout the desired operative stroke withinthe pump barrel. 7

At this point it should be emphasized that the pump barrel is ofsufiicient weight so that by gravity alone, when released by the wireline, it will descend upon its operating or pumping stroke, willcompress the fluid in the pump chamber 26 and force the same through thepassage Sii, the traveling valve 54 and the port 64 into the well casing1% above the packer and thus to the surface. After the downward travelof the barrel and the pumping stroke has been completed, the wire linethen lifts the barrel to its upper position. This upward travelenlarging the chamber 26 produces a suction which opens the standingvalve 38 and takes in a new charge of liquid from the well bore belowthe packer through the tailpipe. At the same time, the traveling valveis closed.

It will be observed that during this reciprocation of the reciprocatingpump barrel relative to the stationary piston, only Slli'llClClltvertical reciprocation is provided through the wire line to etfect thedesired length of pumping stroke, but this stroke terminates short ofengagement of the piston with the bottom plug 28 of the pump barrel.Consequently, the pumping stroke does not in any way loosen the wedgingaction of the two packer sections and this wedging action is thereforecontinuously maintained by the weight of the fluid column in the wellcasing above the packer.

When it is desired to withdraw the device from the well bore for, anyreason, it is merely necessary to pull the wire line a sufficient extentto cause the upwardly rising pump barrel to engage and lift the piston34. This in turn through the piston rod 32 will lift the upper packersection 70 from the lower packer section and thus uncover the unloadingports 1&2 to the interior of the cavity S4 and permit dumping or ventingof the fluid column through the packer assembly and through thetailpipe. With the lifting of the upper section, the radial wedgingaction upon the lower section is released and the latter now contractssufliciently so that when the stop means 92 on the lower end of thepiston rod engages the body 88, the entire assembly can be withdrawn asa unit to the surface.

It should be noted that in this construction, the rigid construction ofthe centralizer 26 in extra spaced relation above the upper end of thepump barrel and rigidly secured thereto as well as the lower packersection and its sliding engagement upon the interior of the well casingit operates as a sliding guide at both ends of the assembly whichthereby prevents rubbing of the pump barrel against the casing thusavoiding damaging wear therebetween.

As will be seen from FIGURE 8, the bore 3% in the end plug 28 isprovided with channels or grooves 31 which establish continuouscommunication with the cylinder below the piston to permit free flow offluid. However, these grooves do not interfere with an adequate guidingengagement of the bore with the rod 32.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly, all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention asclaimed.

What is claimed as new is as follows:

1. A gravity operated bottom hole casing pump assembly comprising incombination a reciprocating pump, a packer assembly and an unloadingvalve, said pump including a relatively stationary piston and areciprocating cylinder barrel slidably surrounding said piston andslidably received in a well casing, a piston rod secured to said pistonand slidably received in said packer assembly, means for fixedlysupporting said packer assembly in fixed position in a well casing, saidpiston rod comprising a hollow tube with an upper end opening into saidcylinder barrel and having its lower end opening into a well casingbelow said packer assembly, said piston rod including discharge portsslidable through and controlled by said packer assembly and constitutingsaid unloading valve.

2. The combination of claim 1 including a centralizer rigidly secured toand disposed in axially spaced relation above said pump barrel and saidpacker assembly being disposed in axially spaced relation below saidpump barrel, said centralizer and packer assembly comprising guides forsaid pump barrel during insertion and withdrawal of the latter in acasing.

3. The combination of claim 1 including a standing valve controllingcommunication between said upper end of said piston rod and the interiorof said pump barrel, a traveling valve upon said pump barrel andcontrolling communication between the latter and the well casing abovesaid packer assembly.

4. The combination of claim 3 including a centralizer slidable in saidcasing and rigidly connected to said pump barrel for slidably guidingthe latter in said casing while allowing liquid flow between saidcentralizer and said casing.

5. A gravity operated bottom hole casing pump assembly comprising incombination a reciprocating pump, a packer assembly and an unloadingvalve, said pump including a relatively stationary piston and areciprocating cylinder barrel slidably surrounding said piston andslidably received in a well casing, a piston rod slidably received insaid packer assembly, means for fixedly supporting said packer assemblyin fixed position in a well casing, said piston rod comprising a hollowtube with an upper end opening into said cylinder barrel and having itslower end opening into a well casing below said packer assembly, saidpiston rod including discharge ports slidable through and controlled bysaid packer assembly and constituting said unloading valve, acentralizer slidable in said casing and rigidly connected to said pumpbarrel for slidably guiding the latter in said casing and allowingcontinuous liquid flow between the centralizer and easing.

6. The combination of claim 5 wherein said packer assembly includes apair of cooperating inner and outer packer section, said outer packersection being of a deformable material capable of radial expansion intosealing engagement with a well casing and being fixedly mounted uponsaid packer assembly supporting means, said outer packer section havinga central cavity which is downwardly convergent from its open upper end,said inner packer section having a conical exterior surface wedginglyreceivable in said cavity for thereby radially expanding the outerpacker section, said piston rod being fixedly secured to said innerpacker section and being slidable through said outer packer section.

7. The combination of claim 6 wherein said piston rod is hollow andestablishes communication between said well casing below said packerassembly and the pump barrel above the pump piston, said piston rodhaving ports opening into said cavity and controlled by said innerpacker section to comprise said unloading valve.

8. The combination of claim 1 including a tail pipe secured to saidpacker assembly for supporting the latter from the bottom of a Wellbore.

9. The combination of claim 8 wherein said tail pipe has perforations inits side wall, said piston rod having its lower end slidable in andcontinuously communicating with the interior of said tail pipe.

10. The combination of claim 9 wherein said piston rod has stop means onits lower end limiting its withdrawal from and for supporting saidpacker assembly.

11. The combination of claim 1 wherein said packer u assembly includescomplementary inner and outer radially deformable sections, saidsections having conical, wedgingly engaged surfaces, one section beingfixedly secured to a packer anchoring means and the other section beingfixedly secured to said piston rod.

12. The combination of claim 11 wherein said lower section is fixedlysecured to said packer anchoring means and has an upwardly divergentconcave conical surface, said upper section being fixedly secured tosaid piston rod and having a conical outer surface wedgingl'y receivedin said concave conical surface.

13. A gravity operated bottom hole casing pump assembly comprising areciprocating pump barrel slidably received in a well casing togetherwith a wire line connected to said barrel for lifting the latter on itsidle stroke, a stationary pump piston slidable within said barrel, :1piston rod secured to said piston and extending beneath said barrel, apair of complementary, cooperating and relatively movable packersections mounted on said piston rod beneath said barrel, one of saidpacker sections being fixedly secured to said piston rod and the otherpacker section slidably embracing said piston rod, said piston rod beinghollow and establishing communication between the interior of said pumpbarrel above said piston and the well casing below said packer sections,a valve chamber provided between cooperating surfaces of said packersections and open to the well casing above the packer sections when thelatter are disengaged, unloading ports in said piston rod opening intosaid valve chamber, standing and traveling valve assemblies controllingthrough said pump barrel.

14. The combination of claim 13 wherein said standing valve assembly isdisposed in said pump barrel and is mounted upon said pump piston andcontrols flow from said piston rod into said pump barrel.

15. The combination of claim 13 wherein said traveling valve assembly ismounted upon said pump barrel upon the exterior thereof.

16. The combination of claim 13 including a perforated sleeve secured toand depending from said other packer section for supporting the latterin a well bore, said piston rod having its lower end freely slidable insaid sleeve.

17. The combination of claim 16 including a stop means on the lower endof said piston rod beneath said other packer section and engageable withthe latter to limit movement of said other packer section from said onepacker section.

References Cited in the file of this patent UNITED STATES PATENTS249,228 Dower Nov. 8, 1881 604,202 Wright May 17, 1898 663,029 HorsleyDec. 4, 1900 1,601,676 Burright Sept. 28, 1926 1,637,629 Winsor Aug.21,, 1927 1,698,797 Howe Jan. 15, 1929 2,111,173 Cox Mar. 15, 19382,247,325 Wagner June 24, 1941 2,876,708 Frost Mar. 10, 1959 2,885,011Frost May 5, 1959

1. A GRAVITY OPERATED BOTTOM HOLE CASING PUMP ASSEMBLY COMPRISING INCOMBINATION A RECIPROCATING PUMP, A PACKER ASSEMBLY AND AN UNLOADINGVALVE, SAID PUMP INCLUDING A RELATIVELY STATIONARY PISTON AND ARECIPROCATING CYLINDER BARREL SLIDABLY SURROUNDING SAID PISTON ANDSLIDABLY RECEIVED IN A WELL CASING, A PISTON ROD SECURED TO SAID PISTONAND SLIDABLY RECEIVED IN SAID PACKER ASSEMBLY, MEANS FOR FIXEDLYSUPPORTING SAID PACKER ASSEMBLY IN FIXED POSITION IN A WELL CASING, SAIDPISTON ROD COMPRISING A HOLLOW TUBE WITH AN UPPER END OPENING INTO SAIDCYLINDER BARREL AND HAVING ITS LOWER END OPENING INTO A WELL CASINGBELOW SAID PACKER ASSEMBLY, SAID PISTON ROD INCLUDING DISCHARGE PORTSSLIDABLE THROUGH AND CONTROLLED BY